Connector having an impedance matching transformer



R. A. MATEER Dec. 14, 1965 Filed NOV. 14, 1962 Illllllll NdE United States Patent O Filed Nov. 14, 1962, Ser. No. 237,461 Claims. (Cl. 336-175) The present invention relates to impedance matching and particularly to a connector providing lossless impedance matching between the circuits connected to the two sides of the connector.

There is a need for elficient convenient radio frequency impedance matching devices, particularly at radio frequencies. The invention meets this need by providing an R.F. connector including a transformer therewithin capable of matching two different prescribed impedances. An autotransformer having a relatively high current carrying capacity is mounted within a preferably standard R.F. connector. Thus a lossless impedance transformation is provided in such a small space that it can be incorporated in the connector itself.

Resistive matching pads are available for matching the impedances of two different circuits. Such devices, however, have the very serious defect of losing in some cases over two-thirds of the signal power in accomplishing the transformation.

It is an object of the invention to provide a connector capable of providing a lossless impedance transformation.

It is another object of the invention to provide an improved R.F. impedance transformer.

Other objects and advantages of the invention will appear from the following description and the accompanying drawings in which:

FIG. 1 is an exploded view of one embodiment of the invention.

FIG. 2 is a circuit diagram of the transformer.

It will be assumed in the following description, for the sake of definiteness, that a 50 ohm coaxial line or circuit is to be connected to a 75 ohm coaxial line or circuit. The components of the connector include a plug 2 of the form shown in FIG. 1. One end of the plug is externally threaded at 4 and carries a jam nut 6. An insulator 8 having a central opening 10 is adapted to be inserted in plug 2 with the head 12 of the insulator abutting internal flange 3. The insulator has an end bore 13. A metallic pin 14, having a split end 15 in which a coaxial conductor may be soldered, projects through opening 10 and forms the left hand terminal of the connector. Pin 17, which is preferably integral with pin 14, projects through transformer 16 and is soldered to contact 18 and pin 19, forming the right hand terminal of the conector. The transformer has an open cylindrical core 20 formed of a plurality of rings and a number of turns of insulated wire 22. For a 50 to 75 ohm transformer five turns of enameled Wire are provided, each passing over core 20 and then through the core substantially parallel to the axis of the core. One end 23 of the winding is soldered to a collar 24 connected with pin 14. The other end 25 of the winding is soldered or otherwise fastened to the inner wall of plug 2 after assembly of these elements. Collar 24 seats in bore 13 of insulator 8.

The elements described above are assembled in plug 2 and then internally threaded receptacle 26 is screwed on threads 4 of plug 2 and locked with jam nut 6. The receptacle has a knurled or roughened grip 28. The receptacle is of a well known type and has a bayonet slot 27 for ready connection to a coaxial cable type con- 3,223,954 Patented Dec. 14, 1965 nector. Receptacle 2 houses contact 18 and pin 19 in a manner similar to that in which elements 14 and 24 are supported in plug 2 by insulator 8. In one embodiment of the invention the receptacle and contact 18 were of the UG-260U type and plug 2 and its associated elements 8 and 14 were of the UG-657U type.

FIG. 2 shows the transformer schematically. There are five turns between points 23 and 25. Pin 17, however, extends through core 20, and, therefore, provides in effect another turn, so that there are six effective turns between point 25 and terminal 19. Thus the autotransformer has a turns ratio of 5:6 and an impedance transformation of 25 to 36. Common impedance operating levels are 50 and ohms, and the particular embodiment described herein provides a good impedance match between these impedance levels without loss. The entire current of the circuit connected to pin 19 flows through the turn formed by pin 17, but this is obviously adapted to carry a rather high current without appreciable loss.

It will be understood by those skilled in the art that, while the invention has been exemplified by a specific embodiment thereof, many variations and modifications thereof may be made Without departing from the spirit and scope of the invention as defined in the following claims.

What is claimed is:

1. A circuit connector comprising first and second terminals, a first conductor extending between and connected to said terminals, a second conductor extending along said first conductor and insulated therefrom, a magnetic core having a central opening and surrounding said first conductor, and an autotransformer comprising a winding on said core each turn of which extends through the opening of the core and along the outside thereof, said winding terminating in an outside portion of a turn connected to said first conductor at a point adjacent to the core, whereby the portion of said first conductor extending through said core effectively constitutes an additional turn of said Winding, the other end of said winding being connected to said second conductor, one of said terminals being an input terminal and the other terminal being an output terminal of the connector.

2. A circuit coupler comprising a connector having an input terminal and an output terminal at opposite ends thereof, a conductor extending between and connected to said terminals, a cylindrical magnetic core having an axial opening through which said conductor extends, and an autotransformer having a winding on said core each turn of which extends through the opening of the core and along the outside thereof, said winding terminating at one end in an outside portion of a turn connected to said conductor, whereby the portion of said conductor extending through said core effectively constitutes an additional turn of said winding, and a second conductor insulated from said first mentioned conductor and extending substantially along the entire length thereof, the other end of said winding being connected to said second conductor.

3. A circuit coupler comprising an electrical connector having first and second terminals at opposite ends thereof, a rigid conductor extending between and connected to said terminals, a metallic housing surrounding said conductor, means for supporting said conductor and insulating it from said housing, a magnetic core in said connector having a central opening surrounding said conductor, and a longitudinally extending autotransformer winding on said core each turn of which passes through the opening of the core and over the outside thereof, said Winding terminating in an outside portion of a turn connected to said conductor, whereby the portion of said conductor extending through said core effectively constitutes an additional turn of said winding, the other end of said winding being connected to said housing.

4. A circuit coupler comprising a coaxial connector having an outer metallic body and first and second terminals within said body at the ends thereof, a conductor extending between and connected to said terminals, insulating means for supporting said conductor in spaced relation to said metallic body, an autotransformer in said connector including a cylindrical magnetic core having a central opening and surrounding said conductor, and a winding on said core each turn of which extends through the opening of the core and along the outside thereof, said winding having one end connected to the body of said connector, said winding terminating at its other end in an outside portion of a turn connected to said conductor adjacent the core, whereby the portion of said conductor extending through said core effectively constitutes an additional turn of said winding.

5. A coaxial connector comprising a metallic housing, a conductor extending through said housing, means for insulating said conductor from said metallic housing, an

autotransformer comprising a magnetic core having an opening through which said conductor extends, and a Winding on said core each turn of which extends through the opening of the core and along the outside thereof, said winding terminating at one end in an outside portion of a turn connected to said conductor, whereby the portion of said conductor extending through said core effectively constitutes an additional turn of said winding, the other end of said winding being connected to said housing.

References Cited by the Examiner UNITED STATES PATENTS 894,620 7/1908 Frank 336-174 X 2,891,223 6/1959 Dolin et al. 333-33 X 2,963,665 12/1960 Bussard 330-175 X ROBERT K. SCHAEFER, Primary Examiner.

JOHN F. BURNS, Examiner. THOMAS J. KOZMA, Assistant Examiner. 

1. A CIRCUIT CONNECTOR COMPRISING FIRST AND SECOND TERMINALS, A FIRST CONDUCTOR EXTENDING BETWEEN AND CONNECTED TO SAID TERMINALS, A SECOND CONDUCTOR EXTENDING ALONG SAID FIRST CONDUCTOR AND INSULATED THEREFROM, A MAGNETIC CORE HAVING A CENTRAL OPENING AND SURROUNDING SAID FIRST CONDUCTOR, AND AN AUTOTRANSFORMER COMPRISING A WINDING ON SAID CORE EACH TURN OF WHICH EXTENDS THROUGH THE OPENING OF THE CORE AND ALONG THE OUTSIDE THEREOF, SAID WINDING TERMINATING IN AN OUTSIDE PORTION OF A TURN CONNECTED TO SAID FIRST CONDUCTOR AT A POINT ADJACENT TO THE CORE, WHEREBY THE PORTION OF SAID FIRST CONDUCTOR EXTENDING THROUGH SAID CORE EFFECTIVELY CONSTITUTES AN ADDITIONAL TURN OF SAID WINDING, THE OTHER END OF SAID WINDING BEING CONNECTED TO SAID SECOND CONDUCTOR, ONE OF SAID TERMIALS BEING AN INPUT TERMINAL AND THE OTHER TERMINAL BEING AN OUTPUT TERMINAL CONNECTOR. 